The long term objectives of this application are to use the transgenic mouse as a model to elucidate the pathogenetic mechanisms responsible for the development of tissue injury and primary hepatocellular carcinoma (PHC) in chronic, human hepatitis B virus (HBV) infection. The specific aims are to determine how closely this model resembles the chronic HBV carrier state in man and to establish the parameters necessary to induce tissue injury and PHC in these animals. HBV transgenic mice have been, and will be, produced by microinjection of unicellular embryos with cloned subgenomic fragments of HBV. Transgenic mice will be selected for pathogenesis studies based on gene expression and host-viral DNA integration sites using radioimmunoassay, immunofluorescence, immunoelectromicroscopy, Northern blotting, Southern blotting as well as cloning and sequencing techniques. Appropriate animals will be analyzed and manipulated immunologically to induce a potentially cytolytic immune response in vivo resulting in tissue injury. Direct and immunologically mediated tissue injury will be monitored by conventional pathologic analysis and animals will be monitored histologically for the development of tumors. The pathogenetic mechanisms responsible for the resultant disease will be analyzed in vitro by appropriate immunologic techniques including assessment of antigen specific helper, suppressor and cytotoxic T cell function, organ transplantation and adoptive transfer experiments as well as analysis of host-viral integration site and the structural organization of the integrated viral DNA sequences. This model provides a unique opportunity to perform experiments that are directly pertinent to the pathology and pathogenesis of the hepatitis B carrier state but are otherwise not possible.